1/* 2 * Copyright (c) 1996-1999 3 * HD Associates, Inc. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by HD Associates, Inc 16 * 4. Neither the name of the author nor the names of any co-contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY HD ASSOCIATES AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL HD ASSOCIATES OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * $FreeBSD$ 32 * 33 */ 34 35/* XXX: The spec says that if _POSIX_C_SOURCE is defined then 36 * _POSIX_SOURCE is ignored. However, this is similar to 37 * the code in the O'Reilly "POSIX.4" book 38 */ 39 40#define _POSIX_VERSION 199309L 41#define _POSIX_SOURCE 42#define _POSIX_C_SOURCE 199309L 43 44#include <unistd.h> 45#include <stdlib.h> 46 47#include <stdio.h> 48#include <string.h> 49#include <errno.h> 50#include <fcntl.h> 51#include <sys/mman.h> 52 53#include <sched.h> 54 55#include "prutil.h" 56 57static FILE *verbose; 58 59static void 60checkpris(int sched) 61{ 62 int smin; 63 int smax; 64 65 errno = 0; 66 67 if ( (smin = sched_get_priority_min(sched)) == -1 && errno) 68 quit("sched_get_priority_min"); 69 70 if ( (smax = sched_get_priority_max(sched)) == -1 && errno) 71 quit("sched_get_priority_max"); 72 73 if (smax - smin + 1 < 32 || smax < smin) { 74 fprintf(stderr, "Illegal priority range for %s: %d to %d\n", 75 sched_text(sched), smin, smax); 76 exit(-1); 77 } 78 79 if (verbose) 80 fprintf(verbose, "%12s: sched_min %2d sched_max %2d\n", 81 sched_text(sched), smin, smax); 82} 83 84/* Set "try_anyway" to quit if you don't want to go on when 85 * it doesn't look like something should work. 86 */ 87static void try_anyway(const char *s) 88{ 89 fputs(s, stderr); 90 fprintf(stderr, "(trying anyway)\n"); 91 errno = 0; 92} 93 94static void q(int line, int code, const char *text) 95{ 96 if (code == -1) 97 { 98 fprintf(stderr, "Error at line %d:\n", line); 99 perror(text); 100 exit(errno); 101 } 102} 103 104int sched(int ac, char *av[]) 105{ 106 int fifo_schedmin, fifo_schedmax; 107 int i; 108 struct sched_param rt_param; 109 int n_instances = 10; 110 int sched; 111 112 verbose = 0; 113 114#if _POSIX_VERSION < 199309 115 try_anyway("The _POSIX_VERSION predates P1003.1B\n"); 116#endif 117 118#if !defined(_POSIX_PRIORITY_SCHEDULING) 119 try_anyway( 120 "The environment does not claim to support Posix scheduling.\n"); 121#endif 122 123 /* Is priority scheduling configured? 124 */ 125 errno = 0; 126 if (sysconf(_SC_PRIORITY_SCHEDULING) == -1) { 127 if (errno != 0) { 128 /* This isn't valid - may be a standard violation 129 */ 130 quit("(should not happen) sysconf(_SC_PRIORITY_SCHEDULING)"); 131 } 132 else { 133 try_anyway( 134 "The environment does not have run-time " 135 "support for Posix scheduling.\n"); 136 } 137 } 138 139 /* Check that the priorities seem reasonable. 140 */ 141 142 checkpris(SCHED_FIFO); 143 checkpris(SCHED_RR); 144 checkpris(SCHED_OTHER); 145 146/* BSD extensions? 147 */ 148#if defined(SCHED_IDLE) 149 checkpris(SCHED_IDLE); 150#endif 151 152 fifo_schedmin = sched_get_priority_min(SCHED_FIFO); 153 fifo_schedmax = sched_get_priority_max(SCHED_FIFO); 154 155 /* Make sure we can do some basic schedule switching: 156 */ 157 { 158 struct sched_param orig_param, shouldbe; 159 int orig_scheduler = sched_is(__LINE__, &orig_param, -1); 160 161 if (verbose) 162 fprintf(verbose, 163 "The original scheduler is %s and the priority is %d.\n", 164 sched_text(orig_scheduler), orig_param.sched_priority); 165 166 /* Basic check: Try to set current settings: 167 */ 168 q(__LINE__, sched_setscheduler(0, orig_scheduler, &orig_param), 169 "sched_setscheduler: Can't set original scheduler"); 170 171 rt_param.sched_priority = fifo_schedmin; 172 173 q(__LINE__, sched_setscheduler(0, SCHED_FIFO, &rt_param), 174 "sched_setscheduler SCHED_FIFO"); 175 176 (void)sched_is(__LINE__, 0, SCHED_FIFO); 177 178 q(__LINE__, sched_getparam(0, &shouldbe), "sched_getparam"); 179 180 if (shouldbe.sched_priority != fifo_schedmin) 181 quit("sched_setscheduler wrong priority (min)"); 182 183 rt_param.sched_priority = fifo_schedmin; 184 185 q(__LINE__, sched_setparam(0, &rt_param), 186 "sched_setparam to fifo_schedmin"); 187 188 rt_param.sched_priority = fifo_schedmin + 1; 189 190 q(__LINE__, sched_setparam(0, &rt_param), 191 "sched_setparam to fifo_schedmin + 1"); 192 193 q(__LINE__, sched_getparam(0, &shouldbe), 194 "sched_getparam"); 195 196 if (shouldbe.sched_priority != fifo_schedmin + 1) 197 quit("sched_setscheduler wrong priority (min + 1)"); 198 199 q(__LINE__, sched_setscheduler(0, SCHED_RR, &rt_param), 200 "sched_setscheduler SCHED_RR"); 201 202 (void)sched_is(__LINE__, 0, SCHED_RR); 203 204 q(__LINE__, sched_setscheduler(0, orig_scheduler, &orig_param), 205 "sched_setscheduler restoring original scheduler"); 206 207 (void)sched_is(__LINE__, 0, orig_scheduler); 208 } 209 210 211 { 212#define NAM "P1003_1b_schedXXXX" 213 char nam[L_tmpnam]; 214 int fd; 215 pid_t p; 216 pid_t *lastrun; 217 218 strcpy(nam, NAM); 219 if (tmpnam(nam) != nam) 220 q(__LINE__, errno, "tmpnam " NAM); 221 q(__LINE__, (fd = open(nam, O_RDWR|O_CREAT, 0666)), 222 "open " NAM); 223 224 (void)unlink(nam); 225 226 p = (pid_t)0; 227 228 write(fd, &p, sizeof(p)); 229 230 q(__LINE__, (int)(lastrun = mmap(0, sizeof(*lastrun), PROT_READ|PROT_WRITE, 231 MAP_SHARED, fd, 0)), "mmap"); 232 233 /* Set our priority at the highest: 234 */ 235 sched = SCHED_FIFO; 236 rt_param.sched_priority = fifo_schedmax; 237 q(__LINE__, sched_setscheduler(0, sched, &rt_param), 238 "sched_setscheduler sched"); 239 240 for (i = 0; i < n_instances; i++) 241 { 242 pid_t me; 243 244 /* XXX This is completely bogus. The children never run. 245 */ 246 if ((me = fork()) != 0) 247 { 248 /* Parent. 249 */ 250 (void)sched_is(__LINE__, 0, sched); 251 252 /* Lower our priority: 253 */ 254 rt_param.sched_priority--; 255 256 q(__LINE__, sched_setscheduler(0, sched, &rt_param), 257 "sched_setscheduler sched"); 258 259 while (1) 260 { 261 q(__LINE__, sched_getparam(0, &rt_param), "sched_getparam"); 262 263 rt_param.sched_priority--; 264 265 266 if (rt_param.sched_priority < fifo_schedmin) 267 exit(0); 268 269 *lastrun = me; 270 q(__LINE__, sched_setparam(0, &rt_param), "sched_setparam"); 271 272 if (*lastrun == me) 273 { 274 /* The child will run twice 275 * at the end: 276 */ 277 if (!me || rt_param.sched_priority != 0) 278 { 279 fprintf(stderr, 280 "ran process %ld twice at priority %d\n", 281 (long)me, rt_param.sched_priority + 1); 282 exit(-1); 283 } 284 } 285 } 286 } 287 } 288 } 289 290 return 0; 291} 292#ifdef STANDALONE_TESTS 293int main(int argc, char *argv[]) { return sched(argc, argv); } 294#endif 295